Bitcoin;s (CRYPTO: BTC) breakout above $80,000 has boosted the altcoin market, with 19 of the 20 largest liquid altcoins joining the rally, according to a Bitfinex report on Thursday.

What Drove BTC Rally?

Bitcoin has gained more than 29% from its range lows after breaking above $67,000 on Aug. 19, but Bitfinex sees $80,000 to $81,000 as a key resistance zone.

Unlike May’s rally, the latest move has been driven largely by aggressive spot demand.

U.S. spot Bitcoin ETFs posted seven straight positive sessions, including $1.92 billion in inflows from Aug. 17-21, absorbing roughly 12 times the Bitcoin mined during that period.

Institutional demand has also spread to altcoins, with Ethereum ETFs recording their strongest weekly inflows since…